Monday, January 27, 2014

Astronomical Observing - Actually Getting Data

Sunset view from 2.1 Meter catwalk.
So after days of writing about cirrus, humidity, and telescope shut downs, I figured it was time to write about the glories of when it works.  It looked a bit cloudy to start the night, and we were wondering how it would go.  But the worst of the clouds have moved through.  We've been chugging along well so far (fingers crossed for more) and hope that more clouds won't come along until after sunrise.

So what are we doing up here, anyway?  We are looking at asteroids, for the most part.  We are getting image data (in a handful of colors) of the Trojan asteroids of Jupiter.  These are a population of asteroids that orbit the sun at the same distance as Jupiter, gravitationally influenced to stay in two groups, 60 degrees in front and behind Jupiter's orbit.  These objects have not been extensively studied, and may hold some keys to the early formation of the solar system as a whole.

Example of our data.  Asteroid highlighted by green circle.
So here we are, getting data on as many of these asteroids as we can.  And the observing program will go on for the next few years, since we need to look at a large number of asteroids in order to draw meaningful conclusions - at least for this study.

Our data roughly looks like this sort of thing.  An image showing stars and our target asteroid.  The telescope has been commanded to compensate for the rotation of the Earth, so the stars look like nice points, even after a long exposure.  The asteroid is moving at a different rate, however, so if you add the various images together, you can see that it has moved relative to the background stars.  So it looks a bit like a smudge or streak, here.  (The 'wavy lines' are not real, they are artifacts of the data and quickie reduction done for this example.)

Jupiter - Always fun, and amazing
Of course, the 'seeing' isn't always perfect.  Even on a nice night like this one, intermittent clouds can go by.  When that happens, we spend a little time on some very bright targets, until we can go back to taking our regular data.  This is what astronomers call 'having fun.' 

Image Credit:  Shot from catwalk, Andy Rivkin @asrivkin on twitter, example of data from our run, and same for Jupiter.

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